Method of preserving wooden marine structures



May 4,1926.

W. F. CLAPP METHOD OF PRESERVING WOODEN MARINE STRUCTURES Filed August 1,

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William F Clcyp aooooooom Patented May 4, 1926.

UNITED STATES PATENT OFFICE.

WILLIAM F. CLAPP, 0F CAMBRIDGE, -MASSACHUSETTS.

METHOD Application parts.

This invention relates to improvements in methods of preserving wooden marine structures, such as, piles, buoys, channel spars, fish traps, weirs, Wooden vessels, scows, etc.,

" and the object thereof is to cause the imlonger service in salt water pregnation of the surface stratum of the structure throughout its entire area with a metallic salt or salts resistant to the attacks of Teredo worms, Limnoria, and other organisms such as barnacles, hydroids, byrozoans, algae, and the like.

More particularly the invention relates to improvements in methods of preserving piles which are subject to submergence in sea water. The most common method of pre serving piles employed at the present time consists in soaking the piles in vats containing creosote under pressure. of preservation-is not permanently effective as the creosote leaches or washes out in relatively short time. Investigation has shown that heavily creosoted piling is frequently entirely destroyed in the short period of three years. Furthermore the penetration of the creosote into the surface is uneven and Teredo worms are enabled to enter thinly coated surfaces or those from which the creosote has been removed.

Another method of protecting piles which has-been used quite extensively in Holland and on the Pacific coast of the United States consists in studding the wood with closely arranged nails having large heads, the nails being driven so closely together that the heads form practically an impenetrable sheathing.

Since early Roman times it has been known that wood filled with large headed iron nails could be depended upon to give than wood not so protected, and it has been found that the iron rust or iron oxide prevented to some extent the rapid growth of the Teredo worm. In tests made by me of this method I found the distribution of the iron rust in the wood the top of the pile,

Such a method OF IPRESERVING WOODEN MARINE STRUCTURES. 4

filed. August 1, 1924. Serial No. 729,491.

to be so slow that frequently the wood would be destroyed before the water had the time to act upon the nails sufliciently to produce such distribution of the iron oxide as to repel the invasion of the Teredo worms. The use of iron and other nails driven into a pile to form a belt encircling the pile where the pile projects from the mud or bottom is disclosed in Patent No.1215,600 granted May 20, 1879 to W. T. Garratt and S. J. Lynch, which patent also discloses means for introducing a chemical solution near the base of the pile which is adapted to produce an oxide which, according to the disclosure of the patent, is distributed upwardly along the pores of the Wood toward this capillary method of distributing the oxide also being relied upon for the protection of the upper surface of the pile where nails are driven into it to form a belt encircling the pile at the point where the pile projects from the mud or bottom. As a result of numerous experiments I have found that such method of distribution of the metal oxide is entirely ineiiicient and unsatisfactory and that the portion of the piling not included Within the band will be quickly sub ect to the ravages of the Teredo there is no such uniformity of distribution as will effectively protect the pile.

Other patented methods of protecting piling and other wooden marine structures eonsist in causing a current of electricity to flow through the pile or other wooden structure, or in proximity thereto, for the purpose of destroying the Teredo by the electric current, or for the alleged purpose of liberating chlorine from the sea water in such quantity as to be destructive to Teredo and other marine pests.

These methods are either inefiicient or costly or both.

The present from the ravages of Teredo worms,-L1mnoria, and other marine organismsdestructive to wooden marine structures was discovered or invented by me in connection with extensive investigations of the ravages produced by such marine pests, mainly the Teredo worm, in various harbors, together with the study and classification of numerous of such specimens with respect to'their locality, characteristics, rate of growth, food supply, length of life, and other biological factors, and in connection with numerous exmethod of protecting piles pernnents conducted by me for the purpose of determining possible means of preventing or reducing the attacks of such organisms upon wooden marine structures. As a result of such investigation and ex )eriments I discovered that the entire surface stratum of the wooden structure, which is subject to saturation by a saline solution, such as sea water, could be thoroughly impregnated with a metallic compound or compounds having properties fatal to or resistant to the attack of destructive marine organisms, such compound or compounds being produced and distributed by electro-chen'iical or electrolytic action induced in the saturated surface stratum by the presence of a plurality of metallic members of different electro-motive force or polarity located in proximity to each other, such different metallic members either being in contact, or in relatively narrowly spaced proximity to each other.

I found that metallic members of different electro-motive force or polarity, particularly members composed respectively mainly of iron and copper, associated either in contact or in narrowly spaced relation, and applied to the surface stratum, either by superficial close contact or by being en'ibedded therein, would, upon saturation of the surface area of the wooden structure to a substantial depth, produce a distribution of a compound or compounds Which, I believe, is largely iron oxide, throughout the saturated surface stratum to a depth suificient to prevent effectively the ravages of such destructive marine organisms.

\Vhile I am unable to state positively the character of the electro-chemical or electrolytic action which causes the production and thorough impregnation of the surface stratum which is subject to submergence, it is a fact that such impregnation occurs only when metallic members or materials having different electro-motive force or polarity are employed. The terms electro-chemical reaction or electrolytic action used in the specification and claims, therefore, refer to the resulting phenomenon which takes place by reason of the presence of a plurality of metallic members of force or polarity induced in the surface stratum which is saturated with a saline solution, whether by reason of the presence of the saline solution alone or in combination or association with the constituents of the wooden material of the structure, such as, tannic acid, or a derivative thereof, or gallic acid, pyrogallic acid, or salts of the same and substances of like nature which are present in Wood.

I also found by experimentation that if the :iles, or other wooden structures, which had ween treated by the method of preservation embodying the present invention, were subject to the action of sea water a Su ficient' different electro-motive' length of time before the active seasons of the Teredo and other marine pests the metallic compound or compounds would be so thoroughly distributed through the surface stratum that the piles and other Wooden structures would be free from attack of these marine pests.

I also discovered that where piles and other wooden structures which had been freshly subject to the method of preservation forming the present invention were placed in the sea water during the active period of the Teredo worms, such Teredo worms as had penetrated the surface of the pile or other wooden structure before said electro-chemical or electrolytic action had progressed were killed by the subsequent impregnation of the wood by such compound or compounds.

Various means were employed for im regnating the surface stratum of the pi e or other wooden structure of which selected illustrative means are illustrated herein in the accompanying drawings. It will, there fore, be understood that any suitable means may be employed in the performance of the method for preserving Wooden marine structures which comprises impregnating with a metallic compound or compounds in the manner aforesaid, the surface stratum of the structure throughout the area which is subject to submergence, that is to say, from the base of the structure or the mud line ofthe pile to the high water mark of the pile or structure which is to be preserved.

In the drawings:

Fig. 1 is a side elevation of a pile having a portion partly broken away and illustrated in section, showing a preferred means for protecting the pile by the-method forming the present invention;

Fig. 2 is a similar view of a pile showing another means of protecting the pile by the method embodying the invention; and,

Fig. 3 is a similar View of a pile showing another means of protecting the pile by the method embodying the invention.

. The illustrated means for performing the method of preserving wooden marine structures which is illustrated in the accompanying drawings as applied to piles comprises securing to or embedding within thesurface stratum of the pile at suitable, preferably substantially uniform, intervals metallic members of different electro-motive force or polarity operable in the presence of seawater to produce an electro-chemical or elec trolytic action which will produce a metallic compound or compounds resistant to the attacks of destructive marine organisms and will cause the same to impregnate to a predetermined depth the surface stratum of the pileor other marine structure.

As illustrated in Fig. 1 this is accomthe pile.

.posed in this malfiier over the entire area -wlnch 1S sub ect to submergence.

When the pile or other wooden marine structure is thus treated a metallic compound or compounds, which tests showis mainly an iron salt such as iron oxide, thoroughly impregnates the surface stratum of the pile or other wooden marine structure which is saturated by the seawater.

By this method the surface stratum is thoroughly impregnatedto a depth approximately equal to and usually slightly beyond the depth of penetration of the nail so that not only the surface of the wood, but a considerable depth of the outer portion of the pile is protected against the ravages of the Teredo worm, and crustacea, and other organisms which are harmful to the pile or structure, as none of these pests will attack or enter any portion of the pile, or other wooden structure, which is thus impregnated by the preservative. v -The nails which are thus introduced into the pile present heads which protect the pile from abrasion and thereby prolong the life of the pile. Furthermore, if any of the surface ofthe pile which is thus treated is struck a heavy blow thenails will be forced further into the pile and the electrolytic action will liberate and distribute the oxide through an area of still greater depth within vIt will be understood, of course, that other materials of different electro-motive force or of opposite polarity may be employed and that when so employed other metallic compounds than the compounds of iron will be liberated and distributed through the surface stratum of the pile or other wooden marine structure in the manner above described.

A different means for performing the method embodying the invention is illustrated in Fig. 2 in which the pile 5 is provided with a plurality of rows of nails 6 of iron having washers 7 of copper, or other material of different electro-motive force than iron, placed beneath the heads of the iron nails and securely held against the surface-of the pile or other wooden structure. In this construction the nail, with the copper washer beneath its head. forms an electric couple and the lines of flow of the current within the pile extend not only from the shank of each nail in more or less curved lines to the' washer beneath the head of the nail, but from the shank of each nail to the washers of other nails which are located in proximity thereto. Thus the surface stratum of the pile or other structure is impregnated thoroughly and to a considerable depth with the metallic oxide in the manner heretofore described.

In Fig. 3 another means is illustrated for impregnating the surface stratum of the pile and consists in surrounding the pile, at preferably substantially equal intervals, with alternating strands 11 and 12 of suitable material, such as, copper and iron respectively. In this construction the impregnation of the metallic compound or compounds extends in curved lines, as illustrated, well beneath the surface of the pile.

It has been found by actual experiment that piles, and other wooden marine structurcs, to which the above described method of preserving has been applied have been thoroughly protected from the ravages of Teredo worms in prolonged periods in southern waters where the Teredo worms are most active and that the method has also been demonstrated to be thoroughly effective against the ravages of Limnoria an other incrusting organisms like barnacles, together with hydroids, bryozoans', algae, and other marine pests.

It will, be understood that the particular embodiments of the invention disclosed herein are of an illustrative character and that other suitable materials may be employed in the performance of the method or process defined in the following claims.

Having thus described the invention, what is claimed as new. and desired to be secured by Letters Patent, is:

1. The method of preserving wooden marine structures which comprises impregnating the entire surface stratum of the structure, which is subject to submergence and saturation by saline solution, with a metallic compound or compounds having properties resistant to the attack of destructive marine organisms, produced and distributed by electro-chemical reaction induced in said saturated surface by the presence of a plurality of metallic members of different electro-motive force located in proximity to each other and distributed throughout the area which is subject to submergence.

2. The method of preserving wooden marine structures which comprises impregnating the entire surface stratum of the structure, which is subject to submergence and saturation by saline solution, with a metallic compound or compounds having properties resistant to the attack of destructive marine organisms, produced and distributed by electro-chemical reaction in- .organisms, produced and distributed by duced in said saturated surface by the presonce of ferrous and cuprous materials applied to said surface stratum and distributed throughout the area Which is subject to submcrgence.

3. The method of preserving wooden marine. structures which I comprises impregnating the entire surface stratum of the structure, which is subject to submergence and saturation by saline solution, with a metallic compound or compounds having properties resistant to the attack of destructive marine electro-chemical reaction induced in said saturated surface by the presence of rigid members composed respectively mainly of iron and of copper applied to said surface stratum in proximity to each other and-in alternating relation at substantially uniform intervals throughout the area which is subject to submergence.

4. The method of preserving wooden marine structures which comprises impregnating the entire surface stratum of the struc ture, which is subject to submergence and saturation by saline solution, with a metallic compound orcompounds having properties resistant to the attack of destructive marine organisms, produced and distributed by electro-chemical reaction induced in said saturated surface .by the presence of. rigid ferrous members embedded in said surface stratum and associated with cuprous members applied to said surface stratum in proximity to said ferrous members.

5. The method of preserving wooden marine structures which comprises applying to the surface stratum of the structure, which is subject to submergenceand saturation by saline solution, members composed respectively mainly of copper and-iron'associated in proximity to each other throughout theentire area which is subject to submergence.

6. The method of preserving wooden marine structures which comprises inserting into the surface stratum of the structure, which is subject to submergence and saturation by saline solution, a plurality of alternating series. of iron and copper nails spaced at substantially uniform close intervals and distributed throughout the entire area which.

is subject to submergence. v

In testimony whereof, I have signed my name to this specification.

WILLIAM F. CLAPP. 

